[Gate-users] Why the dose of water phantom from Yttrium-90 is nearly double the original estimate?

[李昕迪 Lee, Sin-di]

Hello GATErs:

 I made a simulation with a 1-kg water phantom filled with 1 GBq
Yttrium-90 and recorded the dose of the phantom with a 10*10*10
matrix.

 The code Yttrium-90 source was as following:
/gate/source/Y90/gps/particle ion
/gate/source/Y90/gps/ion 39 90 0 0
/gate/source/Y90/setForcedUnstableFlag true
/gate/source/Y90/useDefaultHalfLife
/gate/source/Y90/setActivity 1 GBq
/gate/source/Y90/gps/angtype iso

 I used the method of setTotalNumberOfPrimaries.

/gate/application/setTotalNumberOfPrimaries 10000
/gate/application/start
exit

 Because the mean energy of the beta ray of Yttrium-90 is 0.9267 MeV,
the estimated dose is 1.4827E-9 Gy. However, the result of simulation
is 3.0259E-9.

 I made another simulation with more primary particles up to 1E6, and
the result is the same.

 Does somebody have a clue?

The full code was here.
https://www.dropbox.com/sh/ixsd7u9t2ikq0qe/AAD-Uep9OuV-8dTYSutn0KPoa?dl=0


 Thanks a lot.


 Sincerely,

Sin-Di Lee


-- 
李昕迪 Lee, Sin-di | http://www.mcdlee.tw